Nothing wrong with that.
>influenced by the earlier computer algebra systems Macsyma (of which Wolfram was a user) and Schoonschip (whose code Wolfram studied).
Not much wrong with that either.
Even if it was just a clone of those systems when it came out, being the successful clone is enough to make it have merit.
But of course since then it's 1000 times the code size of the initial systems, and 100 times the capabilities.
>It would be the same to defend William Henry "Bill" Gates III, by stating that MS-DOS is significant, while MS-DOS was a renamed form of 86-DOS
Again, MS-DOS is significant. Whether it was innovative (it wasn't) is another thing, but it sure has been historically significant.
Sorry, but it's not always the first product that comes out that defines an era and a market. And copying happens all the time too, and can even evolve into something that the original never was.